/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.thrift;

import java.nio.ByteBuffer;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;

import org.apache.thrift.protocol.TField;
import org.apache.thrift.protocol.TProtocol;
import org.apache.thrift.protocol.TProtocolException;
import org.apache.thrift.protocol.TStruct;
import org.apache.thrift.scheme.IScheme;
import org.apache.thrift.scheme.SchemeFactory;
import org.apache.thrift.scheme.StandardScheme;
import org.apache.thrift.scheme.TupleScheme;

public abstract class TUnion<T extends TUnion<?, ?>, F extends TFieldIdEnum>
		implements TBase<T, F> {

	private static final long serialVersionUID = 1L;

	protected Object value_;
	protected F setField_;

	protected TUnion() {
		setField_ = null;
		value_ = null;
	}

	private static final Map<Class<? extends IScheme>, SchemeFactory> schemes = new HashMap<Class<? extends IScheme>, SchemeFactory>();
	static {
		schemes.put(StandardScheme.class, new TUnionStandardSchemeFactory());
		schemes.put(TupleScheme.class, new TUnionTupleSchemeFactory());
	}

	protected TUnion(F setField, Object value) {
		setFieldValue(setField, value);
	}

	protected TUnion(TUnion<T, F> other) {
		if (!other.getClass().equals(this.getClass())) {
			throw new ClassCastException();
		}
		setField_ = other.setField_;
		value_ = deepCopyObject(other.value_);
	}

	private static Object deepCopyObject(Object o) {
		if (o instanceof TBase) {
			return ((TBase) o).deepCopy();
		} else if (o instanceof ByteBuffer) {
			return TBaseHelper.copyBinary((ByteBuffer) o);
		} else if (o instanceof List) {
			return deepCopyList((List) o);
		} else if (o instanceof Set) {
			return deepCopySet((Set) o);
		} else if (o instanceof Map) {
			return deepCopyMap((Map) o);
		} else {
			return o;
		}
	}

	private static Map deepCopyMap(Map<Object, Object> map) {
		Map copy = new HashMap();
		for (Map.Entry<Object, Object> entry : map.entrySet()) {
			copy.put(deepCopyObject(entry.getKey()),
					deepCopyObject(entry.getValue()));
		}
		return copy;
	}

	private static Set deepCopySet(Set set) {
		Set copy = new HashSet();
		for (Object o : set) {
			copy.add(deepCopyObject(o));
		}
		return copy;
	}

	private static List deepCopyList(List list) {
		List copy = new ArrayList(list.size());
		for (Object o : list) {
			copy.add(deepCopyObject(o));
		}
		return copy;
	}

	public F getSetField() {
		return setField_;
	}

	public Object getFieldValue() {
		return value_;
	}

	public Object getFieldValue(F fieldId) {
		if (fieldId != setField_) {
			throw new IllegalArgumentException("Cannot get the value of field "
					+ fieldId + " because union's set field is " + setField_);
		}

		return getFieldValue();
	}

	public Object getFieldValue(int fieldId) {
		return getFieldValue(enumForId((short) fieldId));
	}

	public boolean isSet() {
		return setField_ != null;
	}

	public boolean isSet(F fieldId) {
		return setField_ == fieldId;
	}

	public boolean isSet(int fieldId) {
		return isSet(enumForId((short) fieldId));
	}

	public void read(TProtocol iprot) throws TException {
		schemes.get(iprot.getScheme()).getScheme().read(iprot, this);
	}

	public void setFieldValue(F fieldId, Object value) {
		checkType(fieldId, value);
		setField_ = fieldId;
		value_ = value;
	}

	public void setFieldValue(int fieldId, Object value) {
		setFieldValue(enumForId((short) fieldId), value);
	}

	public void write(TProtocol oprot) throws TException {
		schemes.get(oprot.getScheme()).getScheme().write(oprot, this);
	}

	/**
	 * Implementation should be generated so that we can efficiently type check
	 * various values.
	 * 
	 * @param setField
	 * @param value
	 */
	protected abstract void checkType(F setField, Object value)
			throws ClassCastException;

	/**
	 * Implementation should be generated to read the right stuff from the wire
	 * based on the field header.
	 * 
	 * @param field
	 * @return read Object based on the field header, as specified by the
	 *         argument.
	 */
	protected abstract Object standardSchemeReadValue(TProtocol iprot,
			TField field) throws TException;

	protected abstract void standardSchemeWriteValue(TProtocol oprot)
			throws TException;

	protected abstract Object tupleSchemeReadValue(TProtocol iprot,
			short fieldID) throws TException;

	protected abstract void tupleSchemeWriteValue(TProtocol oprot)
			throws TException;

	protected abstract TStruct getStructDesc();

	protected abstract TField getFieldDesc(F setField);

	protected abstract F enumForId(short id);

	@Override
	public String toString() {
		StringBuilder sb = new StringBuilder();
		sb.append("<");
		sb.append(this.getClass().getSimpleName());
		sb.append(" ");

		if (getSetField() != null) {
			Object v = getFieldValue();
			sb.append(getFieldDesc(getSetField()).name);
			sb.append(":");
			if (v instanceof ByteBuffer) {
				TBaseHelper.toString((ByteBuffer) v, sb);
			} else {
				sb.append(v.toString());
			}
		}
		sb.append(">");
		return sb.toString();
	}

	public final void clear() {
		this.setField_ = null;
		this.value_ = null;
	}

	private static class TUnionStandardSchemeFactory implements SchemeFactory {
		public TUnionStandardScheme getScheme() {
			return new TUnionStandardScheme();
		}
	}

	public static class TUnionStandardScheme extends StandardScheme<TUnion> {

		@Override
		public void read(TProtocol iprot, TUnion struct) throws TException {
			struct.setField_ = null;
			struct.value_ = null;

			iprot.readStructBegin();

			TField field = iprot.readFieldBegin();

			struct.value_ = struct.standardSchemeReadValue(iprot, field);
			if (struct.value_ != null) {
				struct.setField_ = struct.enumForId(field.id);
			}

			iprot.readFieldEnd();
			// this is so that we will eat the stop byte. we could put a check
			// here to
			// make sure that it actually *is* the stop byte, but it's faster to
			// do it
			// this way.
			iprot.readFieldBegin();
			iprot.readStructEnd();
		}

		@Override
		public void write(TProtocol oprot, TUnion struct) throws TException {
			if (struct.getSetField() == null || struct.getFieldValue() == null) {
				throw new TProtocolException(
						"Cannot write a TUnion with no set value!");
			}
			oprot.writeStructBegin(struct.getStructDesc());
			oprot.writeFieldBegin(struct.getFieldDesc(struct.setField_));
			struct.standardSchemeWriteValue(oprot);
			oprot.writeFieldEnd();
			oprot.writeFieldStop();
			oprot.writeStructEnd();
		}
	}

	private static class TUnionTupleSchemeFactory implements SchemeFactory {
		public TUnionStandardScheme getScheme() {
			return new TUnionStandardScheme();
		}
	}

	public static class TUnionTupleScheme extends TupleScheme<TUnion> {

		@Override
		public void read(TProtocol iprot, TUnion struct) throws TException {
			struct.setField_ = null;
			struct.value_ = null;
			short fieldID = iprot.readI16();
			struct.value_ = struct.tupleSchemeReadValue(iprot, fieldID);
			if (struct.value_ != null) {
				struct.setField_ = struct.enumForId(fieldID);
			}
		}

		@Override
		public void write(TProtocol oprot, TUnion struct) throws TException {
			if (struct.getSetField() == null || struct.getFieldValue() == null) {
				throw new TProtocolException(
						"Cannot write a TUnion with no set value!");
			}
			oprot.writeI16(struct.setField_.getThriftFieldId());
			struct.tupleSchemeWriteValue(oprot);
		}
	}
}
